The Franks supported the missionary efforts of Saint Boniface, who cut down the Donar Oak in nearby Geismar and established a short-lived bishopric in Büraburg.
[2] By 650, the Franks were establishing themselves as overlords, which is suggested by archeological evidence of burials, and were building fortifications in various places including Christenberg.
Walls and trenches totaling one kilometer in length were made, and they enclosed "8 hectares of a spur that offered a commanding view over Fritzlar and the densely populated heart of Hessia".
[5] The presence of a mounted garrison is deduced from archeological finds, including spurs, harness fittings, and fragments of weapons.
[11] In 723 AD the Anglo-Saxon missionary Saint Boniface arrived in the area on his mission to convert the central and northern German tribes to Christianity.
Seeking to demonstrate the superiority of Christianity, he and his followers felled a sacred oak dedicated to the god Donar (Thor) by the local tribe of the Chatten/Chatti.
[12] Using the wood of the oak, Boniface erected a small chapel dedicated to Saint Peter at a site nearby, in what soon became the important religious, intellectual, and trade center of Fritzlar.